Motor fuels



Patented Oct. 24, 1 944 UNITED PATENT OFFICE Ernest F. revere, Beacon,N. Y., assignor, by mesne assignments, to The TexasGomp'any, New York; Ni Y., a corporation of Delaware have shown antilinock values of theblend substantially below average of the antiknock values of therespective hydrocarbons. This indicates that there is an incompatibilitywith respect to antiknock properties of hydrocarbon mixture such asoccur in gasoline.

For example, aromatic hydrocarbons have a high antiknock value but, whenthese hydrocarbons are blended with straight chain paraflinhydrocarbons, particularly the higher molecular weight normalparafiins', such as occur in the higher boiling fractions of gasoline,there is an unexpected depreciation in the antiknock value of thearomatics. Thus the octane number of benzene alone is about 111.6whereas in blends of ordinary gasoline the blending antiknock number ofa 50% blend of benzene is about 85 as tested by the C. F. R. M. method.

The reasons for this incompatibility are not fully understood but it isthought that it may be due to the oxidation of the less stable lowantiknock hydrocarbons, whereby the more stable, high antiknockhydrocarbons are reacted upon below their normal combustion temperature.

It has been found that an improved motor fuel may be obtained byblending aromatic hydrocarbons with a more stable type of parafiinhydrocarbons, such as isoparaffins and low molecular .weight normalparafiins. The following data show the octane number of certainhydrocarbons and blends thereof with benzene:

A plication October 14,1939, Serial No. 299,513

. Blending Composition 8?fiiii iifiiti benzene 100% isopentane 89. 4 50%isopentsne and 50% benzene... 91. 6 93 8 100% commercial iso-octane 96.3 50% commercial iso-octane and 50% benzene 95. 8 95. 8 100% normalpentane 50% normal pentane and 50% benzene 78 96 It will be noted fromthe above data, wherein benzene is blended with certain selectedhydrobenzene is about 95, as compared with when the benzene is blendedwith ordinary gasoline.

In accordance with the invention, an improved motor fuel is obtained byblending aromatic hydrocarbons with isoparafii'n hydrocarbons ofgasoline boiling range and low molecular weight normal parafiins of lessthan 6 carbon atoms, for example para-fi'lns of 4 to 5 carbon atoms.

The aromatic hydrocarbons may be substan tially pure aromatics, such asbenzene or toluene. The aromatic hydrocarbons may be obtained from anaromatic fraction boiling above about 160 F. of cracked gasoline bysolvent extracting the aromatics with a suitable solvent such as sulfurdioxide or any other solvent having properties for selective extractionof the aromatics.

The isoparafiin hydrocarbons may be substantially pure isoparafiins,such as iso-octane. The isoparafiln hydrocarbons are preferablycommercial products such as an alkylation gasoline or a hydrogenatedpolymer gasoline. The alkylation gasoline is prepared by the alkylationof low boiling isoparaffins, such as isobutane or isopentane witholefins, such as normally gaseous olefins or polymers thereof, in thepresence of an alkylation catalyst, such as sulfuric acid and aluminumchloride. The hydrogenated polymer gasoline is produced by thehydrogenation of polymers resulting from the selective polymeriza tionof isobutylene' or interpolymerization of isobutylene and normalbutylenes. The alkylation gasoline or the hydrogenated polymer gasolinemay be a broad boiling range liquid fraction with an endpoint up to 400F. or it may be a lighter out, such as 311 F. endpoint fraction.

In the case where the broad boliing range frac tion is employed, or inany other case where found desirable, the blend of the aromatic fractionwith the alkylation or hydrogenated polymer gasoline may be adjusted asto its light end boiling range by the addition, preferably, of a desiredproportion of C4 or C5, or a mixture of C4 and Cs saturated parafiinhydrocarbons, which may be obtained from the stabilization ordebutanization of natural or straight run gasoline.

By way of further examples of the present invention, an alkylation motorfuel gasoline, having a boiling rangeof approximately to 400 F. blendedin the proportion of 75-25% by volume with 25-75% of an Edeleanu extractof a cracked gasoline having a boiling range of approximately to 400 F.,produces a motor fuel of unusually high C. F. R. M. octane of the orderof 90-95 with satisfactory distillation charactercarbons, that theblending octane number of the 5 istics and Reid vapor pressure.Similarly, a light polymer gasoline produces a motor fuel of good octaneof the order of 80-85 with suitable distillation characteristics andReid vapor pressure.

Obviously many modifications and variations of the invention, ashereinbefore'set forth, may be made Without departing from the spiritand scope thereof, and therefore only such limitationsnumber by the C,F. R. M. method of a 50% should be imposed as are indicated in theappended claims.

I claim:

1. A motor fuel comprisinga stantial and effective proportion not inexcess or about 75% of an. aromatic hydrocarbon boiling within thegasoline boiling range with at least 25% of a synthetic saturatedparafiinic gasoline blend of a sub- 3. A motor fuel of high anti-knockvalue comprising a blend of a substantial proportion not in excess ofabout 50% of an aromatic hydrocarbon boiling within the gasoline boilingrange with at least 50% of a saturated paraifinic gasoline fraction ofbroad boiling range and consisting essentially of a synthetic mixture ofisoparaflinic hydrocarbons including iso-octane, said motor fuelbeingsubstantially free from normal paraflin hydrocarbons of higher molecularweight than normal pentane such that the blending octane blend ofbenzene with the saturated paraffinic components of the; fuel is atleast about 93.8.

excess of about 50% by volume of an aromatic hydrocarbon boiling withinthe gasoline boiling 'rangefand at least 50% by volume of a saturatedparaffinic gasoline fraction of broad boiling range, the C6 and higherhydrocarbons of said fraction consisting essentiallyof a syntheticmixture of lisop'araifinicj hydrocarbons including iso-octane selected.from the group consisting of hydrogenated polymer gasoline andisoparaffinolefin alkylate, said motor fuel being substantially freefromnormal paraffin hydrocarbons of higher molecularweight than normalpentane.

' ERNEST F. PEVERE.

